feat(worldline): checkpoint-tree rewind for tui_v2 (#625)

* fix(continue): preserve session workspace on in-place restore

In-place /continue retargets agent.log_path to the restored file, so the
reset bind `_bind_workspace(None)` ran during restore was persisting
session_ws_set(path, "") — erasing that session's own workspace mapping to
"" (read back as "explicitly off") before we read it, which also short-
circuited the log-scan fallback. The continued session never re-entered its
workspace.

Add a `persist` flag to `_bind_workspace`; the restore-time reset passes
persist=False so it only refreshes in-memory state. The session→workspace
map is now written solely by explicit /workspace, /workspace off, and a
successful restore.

* fix(tui_v3): support Home/End keys for line start/end

PTK delivers Home/End as raw VT sequences in KeyPress.data, which
_esc_repl swallowed (only arrows were decoded). Map \x1b[H/[F/[1~/[4~
and SS3 \x1bOH/\x1bOF to internal bytes 0x07/0x14, extend _ESC_RE to
match SS3 as whole sequences, and add jump-to-line-start/end handlers
in _keys. Home no longer collides with Ctrl+A select-all.

* feat(worldline): integrate checkpoint-tree rewind into tui_v2

- tuiapp_v2.py: /rewind durable inline picker + /worldline three-pane
  checkpoint tree (tree UI inlined; colors follow the v2 theme) with a
  per-node diff viewport; conv-only /rewind restores via the persistent store.
- worldline.py (new): UI-agnostic backend — RewindStore (persistent
  checkpoint tree + content-addressed blobs), reconcile, restore_plan,
  node_diff, native-log projection.
- continue_cmd.py: gated worldline support — list_sessions(rewind_root=),
  continue_inplace/copy(allow_empty=); default-off, other UIs byte-identical.
- tui_v3.py: status line shows concrete model id (unrelated minor tweak).

* feat(worldline): /rewind reuses the restore-mode picker (conv/code/both)

After picking a turn, /rewind now opens the same RestoreModeScreen as
/worldline to choose conversation / code / both, then restores via the
persistent store — making /rewind a true lite view of /worldline (linear
list, no tree/diff) over the identical restore backend.

Author: nianyucatfish

frontends/continue_cmd.py

@@ -294,7 +294,7 @@ def _rounds_for_file(path, st):
     return n, key
 
 
-def list_sessions(exclude_pid=None, exclude_log=None):
+def list_sessions(exclude_pid=None, exclude_log=None, rewind_root=None):
     """Newest-first list of (path, mtime, preview_text, n_rounds). Preview uses head/tail window only.
 
     `exclude_log` (basename, e.g. 'model_responses_123456.txt') drops the caller's
@@ -324,6 +324,43 @@ def list_sessions(exclude_pid=None, exclude_log=None):
         valid_keys.append(key)
         out.append((f, mtime, preview, rounds))
     _save_rounds_cache(valid_keys)
+    # 【门控·worldline】树感知发现:日志空/缺失但有非空世界线树的会话(回退到起点后日志被
+    # 清空 → 上面 sz<32 跳过了)。仅当调用方显式传 rewind_root 时启用 → 其他 UI 不传,
+    # 行为逐字节不变。只读 tree.json 的 nodes/head(不依赖 worldline 模块)。
+    if rewind_root and os.path.isdir(rewind_root):
+        have = {os.path.basename(p) for p, *_ in out}
+        try:
+            keys = os.listdir(rewind_root)
+        except OSError:
+            keys = []
+        for key in keys:
+            if not key.startswith('model_responses_'):
+                continue
+            log_name = key + '.txt'
+            if log_name in have or log_name == exclude_log:
+                continue
+            log_path = os.path.join(_LOG_DIR, log_name)
+            try:                                    # 仅收"日志确实空/缺失"的(非空日志已被主循环收录)
+                if os.path.getsize(log_path) >= 32:
+                    continue
+            except OSError:
+                pass                                # 缺失也算
+            try:
+                with open(os.path.join(rewind_root, key, 'tree.json'), encoding='utf-8') as fh:
+                    d = json.load(fh)
+            except Exception:
+                continue
+            nodes = d.get('nodes') or {}
+            real = [v for v in nodes.values() if v.get('kind') != 'origin']
+            if not real:                            # 只有 origin 的空树 → 无内容,跳过
+                continue
+            try:
+                mtime = os.path.getmtime(os.path.join(rewind_root, key, 'tree.json'))
+            except OSError:
+                mtime = 0
+            head = d.get('head')
+            title = (nodes.get(head, {}).get('title') if head else '') or '（已回退至会话起点）'
+            out.append((log_path, mtime, f'[世界线] {title}', len(real)))
     out.sort(key=lambda x: x[1], reverse=True)
     return out
 _MD_ESCAPE_RE = re.compile(r'([\\`*_\[\]])')
@@ -1014,10 +1051,19 @@ def _load_history_into(agent, path):
     return f'⚠️ 非 native 格式，降级恢复 {n} 轮摘要（{name}）', False
 
 
-def continue_inplace(agent, path, agent_id=None):
+def _is_empty_log(path):
+    """日志空(<32 字节)或缺失。用于 allow_empty:回退到会话起点后日志被清空的会话。"""
+    try:
+        return os.path.getsize(path) < 32
+    except OSError:
+        return True
+
+
+def continue_inplace(agent, path, agent_id=None, allow_empty=False):
     """原地续:把 agent 的日志指回 `path` 本身,之后轮次追加到 X,延续同一会话。
     调用方应已确认空闲(session_occupant 为 None);抢锁失败(被占)返回错误。
-    返回 (msg, ok)。"""
+    `allow_empty`(仅 worldline UI 传):日志为空时不报错,按【空会话】恢复(清空对话,
+    由调用方按 `.ga_rewind` 树重连),用于"回退至会话起点"的会话。返回 (msg, ok)。"""
     try: agent.abort()
     except Exception: pass
     if not acquire_lock(path, agent_id):       # 先抢到目标锁;失败则保持现状,不丢自己的锁
@@ -1026,10 +1072,14 @@ def continue_inplace(agent, path, agent_id=None):
     if cur and os.path.basename(cur) != os.path.basename(path):
         release_lock(cur)                       # 目标到手,旧会话释放为空闲(同一文件则不放)
     _retarget_log(agent, path)
-    return _load_history_into(agent, path)
+    msg, ok = _load_history_into(agent, path)
+    if not ok and allow_empty and _is_empty_log(path):
+        _replace_backend_history(agent, [])     # 空会话:清空对话(载入失败时它没被清)
+        return '✅ 已恢复空会话（回退至会话起点；世界线树已重连）', True
+    return msg, ok
 
 
-def continue_copy(agent, path, agent_id=None):
+def continue_copy(agent, path, agent_id=None, allow_empty=False):
     """拷贝续:铸新 logid、把 `path` 内容拷进去,在副本上续;`path` 原件不动。
     用于"被占用→用户选拷贝"以及快照源。返回 (msg, ok)。"""
     try: agent.abort()
@@ -1042,7 +1092,11 @@ def continue_copy(agent, path, agent_id=None):
         pass
     acquire_lock(newp, agent_id)
     _retarget_log(agent, newp)
-    return _load_history_into(agent, newp)
+    msg, ok = _load_history_into(agent, newp)
+    if not ok and allow_empty and _is_empty_log(newp):
+        _replace_backend_history(agent, [])
+        return '✅ 已恢复空会话（回退至会话起点；世界线树已重连）', True
+    return msg, ok
 
 
 def install(cls):

frontends/tui_v3.py

@@ -877,10 +877,12 @@ def has(*needles: str) -> bool:
         return b'\x02'
     if has('right'):
         return b'\x06'
+    # Home/End get dedicated bytes — 0x01 is already Ctrl+A (select-all) and
+    # 0x05 has no editor handler, so reusing them would break/no-op the keys.
     if has('home'):
-        return b'\x01'
+        return b'\x07'
     if has('end'):
-        return b'\x05'
+        return b'\x14'
     if has('delete'):
         return b'\x7f'
     if has('backspace') or data == '\x7f' or data == '\x08':
@@ -1496,6 +1498,15 @@ def llm_name(self) -> str:
         except Exception:
             return '?'
 
+    @property
+    def llm_model(self) -> str:
+        """The concrete model id in use (e.g. claude-opus-4-8), not the
+        channel group `llm_name` returns. Empty string when unavailable."""
+        try:
+            return self.agent.get_llm_name(model=True) or ''
+        except Exception:
+            return ''
+
     def list_llms(self) -> list[tuple[int, str, bool]]:
         return self.agent.list_llms()
 
@@ -1632,7 +1643,9 @@ def repl(m: re.Match) -> str:
             out.append(t); i += 1
         return '\x1b[' + ';'.join(out) + 'm' if out else '\x1b[0m'
     return _SGR_RE.sub(repl, s)
-_ESC_RE = re.compile(rb'\x1b\[[0-9;?]*[ -/]*[@-~]|\x1b.')
+# CSI (`\x1b[…`) or SS3 (`\x1bO…`, application-cursor mode for Home/End/arrows)
+# as whole sequences, else any 2-byte `\x1b.` — order matters so SS3 wins over `\x1b.`.
+_ESC_RE = re.compile(rb'\x1b\[[0-9;?]*[ -/]*[@-~]|\x1bO[@-~]|\x1b.')
 _FILE_REF_RE = re.compile(r'@([\w./\-~]+)')
 _PASTE_PH_RE = re.compile(r'\[Pasted text #(\d+) \+\d+ lines\]')
 _FILE_PH_RE = re.compile(r'\[File #(\d+)\]')
@@ -2107,6 +2120,13 @@ def _esc_repl(m: re.Match) -> bytes:
         return b'\x1d'   # Shift+↓ → extend selection down
     if s in (b'\x1b[27;2;13~', b'\x1b[13;2u'):
         return b'\n'      # Shift+Enter (modifyOtherKeys / kitty) → newline
+    # Home/End arrive as raw VT sequences via PTK's KeyPress.data (special keys
+    # carry their original escape bytes), so _ptk_keypress_to_bytes returns them
+    # verbatim and they must be decoded here like the arrows above.
+    if s in (b'\x1b[H', b'\x1b[1~', b'\x1b[7~', b'\x1bOH'):
+        return b'\x07'    # Home → internal jump-to-line-start
+    if s in (b'\x1b[F', b'\x1b[4~', b'\x1b[8~', b'\x1bOF'):
+        return b'\x14'    # End → internal jump-to-line-end
     return b''            # swallow every other escape sequence
 
 
@@ -2496,7 +2516,9 @@ def __init__(self) -> None:
     # in callers are harmless legacy resets (they zero state PTK ignores).
 
     def _status_line(self, w: int) -> str:
-        name = self._bridge.llm_name if self._bridge else '?'
+        # Show the concrete model id; fall back to the channel group only when
+        # the model is unavailable (e.g. a mixin without a single .model).
+        name = (self._bridge.llm_model or self._bridge.llm_name) if self._bridge else '?'
         if self._asking:
             state = _t('status.asking')
         elif self._running:
@@ -5677,6 +5699,14 @@ def _keys(self, data: bytes) -> None:
             elif o == 0x01:                       # Ctrl+A — select all
                 if self.buf:
                     self._sel = 0; self.pos = len(self.buf)
+            elif o == 0x07:                       # Home — jump to line start
+                self._sel = None
+                _, _, ls, _ = self._line_region()
+                self.pos = ls
+            elif o == 0x14:                       # End — jump to line end
+                self._sel = None
+                _, _, _, le = self._line_region()
+                self.pos = le
             elif o == 0x18:                       # Ctrl+X — cut selection
                 r = self._sel_range()
                 if r: